There's a big difference between "cannot" write neatly and "chooses not to."
Sometimes it's more complex than that. Kids with handwriting disabilities sometimes "draw" their letters rather than "writing" them if they have to be neat-- engaging the "wrong" part of the brain, and making it really hard to focus on content and the actual production of writing at the same time.
One of my kids can either write legibly or keep track of his thoughts, but not both at the same time. Thanks to serious motor planning issues, the writing takes up most of his available brainpower. Typing is improving things somewhat.
